This type of band detection sensor includes a light emitter for radiating detection light onto a traveling web, a light receiver for receiving the detection light reflected by the web and outputting a detection signal corresponding to the intensity of the detection light, and a discrimination unit for discriminating the presence of bands on the web on the basis of the detection signal from the light receiver (cf. Patent Document 1). Specifically, the discrimination unit compares an average peak value of the detection signal with a threshold value, and generates a band signal indicative of the presence of a band if the average peak value exceeds the threshold value.